The UK, like other developed countries, is experiencing a marked change in the age structure of its population, characterised by increasing life expectancy and continuing growth in the older fraction of the population [1–4]. Contrary to all major forecasts by national and international agencies over the last few decades, life expectancy has not reached a plateau but has continued to increase by about two years per decade [5–7]. In addition to the obvious reasons for the priority assigned to improving the health and care of older people within the UK through activities such as the NHS Strategic Review of Ageing and Age-Associated Disease and Disability  and the National Service Framework for Older People , there is great scientific interest in studying in detail what is happening to the health of the oldest old (over 85 years) and the factors that influence individual health trajectories. These insights are important, not only to inform us about the health status of what is demographically the fastest growing section of the population (about whom there is remarkably little up-to-date information), but also for what they will tell us about the ageing process itself and the factors that affect it. For a very large proportion of medical conditions, age is the single largest risk factor. Gaining new knowledge about why aged cells and tissues are more vulnerable to pathology is likely to catalyse radical new insights and opportunities to intervene. The rapidly declining mortality rates of the very old point to much greater intrinsic malleability in the mechanisms of ageing than has hitherto been appreciated. This fits well with new biological understanding of ageing, which has been led to a significant extent by our own previous research [10–15]; ageing is not programmed but results from a gradual, lifelong accumulation of subtle damage in the cells and tissues of the body over time. This is modulated by genetic factors, chiefly those involved in maintenance and repair (e.g. DNA repair, antioxidant defences). However, the process appears to be susceptible to a wide range of non-genetic factors, particularly nutrition and lifestyle, which in turn may be affected by socioeconomic status. Genes account for about 25% of the variability of human longevity , and the remaining 75% is believed to be due to factors such as nutrition, lifestyle, and socioeconomic variables, but as yet these have not been determined with any precision. This biological understanding is important for the emphasis it places on the life-course nature of the ageing process and its amenability to positive interventions. A striking feature of biological ageing is its marked variability between individuals [17–22]. This is particularly evident among the oldest old where some individuals preserve strikingly high levels of health and functional ability. Understanding the sources of variability in the oldest-old phenotype will be essential to identify factors contributing to malleability of the ageing process.
Very few measures of health status have been applied systematically within the 85+ age group in the UK [23–25] and no study has yet attempted a comprehensive assessment of biological, medical and social characteristics. The MRC Trial of Assessment and Management of Older People in the Community compared different methods of screening and management of older people, excluding those in long stay hospitals and care homes [26–30]. This mainly cross-sectional trial provided valuable baseline health information on 33,000 75+ year olds, including 5000 in the 85+ age group, with some follow-up for mortality and hospital/institutional admissions. Tinker et al , in an analysis of national survey data from the 1990s, compared the housing, general health and care use of people in the 85+ age group to those aged 65–84. The importance of socioeconomic factors for health of those still in employment was shown by the Whitehall Study . The English Longitudinal Study on Ageing  is focusing on interactions between health and socioeconomic status in 11,000 individuals across a broader age range from 50 to 80+; however the information on the oldest old is relatively scarce with only 250 participants aged 85 and over at baseline and potential bias due to the sampling method used. Other previous studies relevant to understanding health among the very old are the MRC Cognitive Function and Ageing Study (CFAS) [34, 35] and the Leiden 85+ Study [36, 37]. CFAS is a population-based study, in six centres in England and Wales (including Newcastle), of people aged 65 or over living in the community, including long-term care institutions. It is a longitudinal study of 13,004 participants sampled in 1990, with the most recent follow up completed in 2003. At baseline, 1508 participants were aged 85 and over. The core aim of CFAS has been to estimate the prevalence and incidence of cognitive impairment and dementia. The most direct investigation of the overall health status of the very old is the Leiden 85+ Study which recruited 599 individuals aged 85 in 1997 (response rate 87%) and followed them, with annual visits, for five years. The Leiden study included measures on a range of health variables, with a particular focus on inflammation and vascular factors.
The Newcastle 85+ Study design has been developed and fully tested during a cross-sectional study of 85 year olds from four Newcastle general practices which was conducted in 2003–2004. Eighty-nine individuals were recruited to the full study (66% of those eligible) with an additional 27 (20% of those eligible) agreeing to review of general practice medical records only. The results and experience of this study helped shape the detailed plans for the main project. Extensive consultation has taken place with local consumer groups together with other stakeholders such as the local primary care trusts, general practitioners, community nursing staff, social services and care home managers. Close links have also been established with local media which will be used to publicise the study.
The Newcastle 85+ Study is designed using experience from the pilot study, from the Leiden group, with whom we have close collaboration, and with expertise gained within MRC CFAS. The Newcastle study will address key questions about health and health-maintenance in the 85+ population, with a particular focus on quantitative assessment of factors underlying variability in health and on the relationships between health, nutrition and biological markers of fundamental processes of ageing. It will include a range of important questions not included in the Leiden study, particularly with respect to detailed analyses of nutrition and biological markers of ageing.
The aims of the Newcastle 85+ Study are to:
Expose the spectrum of health within an inception cohort of 800 85 year-olds, selected without regard to health status as far as is possible, establishing the distributions (especially the variability) of a broad range of health measures within the group.
Examine, in unprecedented detail, health trajectories and outcomes as the cohort ages and their associations with underlying biological, medical and social factors. This longitudinal element will focus on factors contributing to maintenance of health in this age group and assess the predictive value of biological and other markers of health as measured at baseline.
Advance understanding of the biological nature of ageing.